1. Field of the Invention
This invention relates to a drive tool and, more particularly, to an apparatus and method for performing operations in limited space work areas.
2. Description of the Prior Art
Many working environments include inaccessible or limited space work areas, such as subterranean keyhole excavation spaces, underground vaults, sewers, tanks, storage bins, diked areas, vessels, silos, and other confined spaces. A confined space generally has limited or restricted means of entry or exit. A confined space is accessible to workers to the extent that it is large enough to enter and perform assigned work and is not designed for continuous occupancy. The hazards associated with a confined space may include storage of hazardous material, usage of hazardous material, hazardous activities or other activities associated with the external environment.
Many workplaces contain spaces that meet the regulatory definitions of a confined space because their configurations impede the activities of workers who must enter and exit the space to perform work. Also, workers encounter workplaces where work is to be performed in a space that is completely inaccessible to the extent that the workers must operate tools from a position remote from or out of the inaccessible area. In many instances, a worker will face increased risk of serious physical injury, entrapment engulfment, exposure to hazardous materials, or hazardous atmospheres. Hazardous atmospheres include atmospheres that include flammable, toxic, irritating, or corrosive components.
Some confined spaces are “permit-required” confined spaces. Permit-required confined spaces may contain or have the potential to contain a hazardous atmosphere. Permit-required confined spaces may also contain a material that has the potential to engulf an entrant. Permit-required spaces may also have an internal configuration that might cause an entrant to be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross section. Permit-required confined spaces may contain any other recognized serious safety or health hazards.
The need to minimize disruption to the surrounding landscape has led to the development of minimally invasive technology or subterranean “keyhole” excavations. Subterranean keyhole excavation involves performing work above ground using extension tools to access valves, couplings, and the like on a subterranean natural gas pipeline or water line. The objective of subterranean keyhole excavation is to perform as much work underground in a confined space with the smallest possible ground opening. A small opening is cut in the pavement so that earthen material around the pipe is excavated to provide access to a particular section of the pipeline. The target holes are typically 18 inches in diameter but may be as small as 12 inches in diameter. Typically, a valve or some fixture is replaced or repaired. These operations are performed by using tools that extend through the keyhole to the underground pipeline.
The tools used in keyhole operations require manipulation by extension rods. The tool is used to access the equipment, such as a wrench, pipe cutter, cleaning tool, or grinding tool mounted on the end of an extension rod. Conventionally the tools are mounted at right angles on the extension rods. Because the tool is fixed in its angular position, it cannot be adjusted to engage the equipment if the right angle mounted tool can not be aligned with the equipment. For example, in the case of a ratchet used to disassemble a value on a pipeline in a keyhole operation, the ratchet must be mounted on the end of an extension tube. With the ratchet connected to the extension tube it may be difficult to align the ratchet drive at a right angle with a nut or a bolt on the valve. The ratchet on the end of the tube may not line up with the valve or coupling connection.
Most conventional wrenches use a left to right swinging motion to function. This motion is limited or prohibited in keyhole operations. In most cases, rotation and vertical up and down motion are the only motions available in keyhole operations. Therefore, there is a need in keyhole operations for a tool that generates rotation about the vertical axis to operate tools that transmit rotation from right perpendicular to left perpendicular of the vertical axis. In addition there is need for a tool that overcomes the problems of misalignment in transmitting rotation along a longitudinal axis to an axis perpendicular thereto.
Various extension tools have been disclosed for performing conventional torque transmitting operations. In one example, U.S. Pat. No. 5,396,820 discloses an extensible wrench handle having a removable wrench head. The handle includes a tubular member with a telescoping portion extending therefrom. The telescoping portion is connected to the tubular member through a conventional fastening mechanism. The wrench head is pivotally attached to the telescoping portion.
U.S. Patent Application Publication No. 2006/0000320 discloses a ratchet tool assembly for underground work having an elongated handle member, a elongated release rod, a plate assembly, a ratchet mount plate, a rotatable shaft, a toothed ratchet, and a wrench head. The wrench head includes teeth that engage a bolt head, nut or the like on an underground pipe. The release rod is mounted on the handle member which carries a plate assembly. A ratchet mount plate is pivotally mounted by a rotatable shaft to the plate assembly. Rotation of the shaft generates rotation of the ratchet. The release rod, shaft, and ratchet cooperate to drive the wrench head to engage the bolt head, nut, or the like on the pipe.
U.S. Pat. No. 1,903,660 discloses a flexible wrench having a rotatable shaft mounted within a housing. The shaft has a tee-handle on one end and engages a plurality of extension elements on the opposite end. The shaft rotates the extension elements so that the extension elements rotate a socket element.
U.S. Pat. No. 4,907,476 discloses a socket wrench having an extended tubular casing that supports a gear shaft. The socket wrench also includes the rotatable shaft, a bevel gear, a bevel pinion, a tubular casing, a housing, and a drive shaft. The rotatable shaft includes a tee-handle mounted thereon. The shaft is mounted within the casing, and the shaft rotates the bevel gear which rotates the bevel pinion. The bevel pinion rotates the drive shaft to in turn rotate the wrench head.
U.S. Pat. No. 3,847,039 discloses a valve stem rotating head having a worm wheel mounted within a housing. The head is connected to a rotating shaft which engages the worm wheel to rotate a countershaft that extends into a hole within the ground. The countershaft engages a joint to rotate a socket that engages a valve stem within the hole.
U.S. Patent Application Publication No. 2000/0134674 discloses a hydraulic power tool for servicing pipes. The tool includes a hydraulic motor or swivel housing attached to an extensible mounting frame. A rotatable shaft extends from the frame in a perpendicular direction into a hole in the ground. A pair of flexible air hoses are attached to the shaft.
U.S. Pat. No. 5,570,581 discloses a hydraulic valve operator mounted on a sectional frame. The frame includes a frame section that extends from the back of a pick-up truck bed. A hydraulic motor is mounted on the frame section. A drive rod extends through the hydraulic motor so that the drive rod is perpendicular to the frame section. The hydraulic motor rotates the drive rod which extends into a hole in the ground where the drive rod engages an underground valve.
U.S. Pat. No. 3,972,506 discloses a device for opening and closing a valve. The device includes a powered valve opening and closing unit, a flexible rotary shaft, and a worm gear. The shaft is rotated in driving engagement with the worm gear to in turn open and close the valve.
U.S. Pat. No. 3,585,885 discloses an adjustable tool handle having a pair of terminal fittings that are connected to one another with a flexible tension member. The tension member includes a plurality of tubular components. The terminal fitting can be connected to a wrench head.
U.S. Pat. No. 4,730,960 discloses a flexible socket extension. The extension includes a pair of end caps that are connected by a flexible cable. One of the end caps engages a female connector, such as a socket.
While it is known to use drive tools that are extended into limited space work areas, and inaccessible work areas, such as areas excavated in keyhole operations, there is need for a drive tool that can extend into a limited space work area for transmitting rotation to equipment on a pipeline through a range of angles which are not limited to 90°. Even though the drive tool is mounted at a 90° angle relative to the shaft of the extension tool, the angular position of the drive tool must be adjustable so as to overcome misalignment problems with the equipment on the pipeline.